Owen Duffy wrote:
I say that the phase relation MUST be the same everywhere on the coil.

That does not seem to me to support Cecil's proposition at all, I
understand Cecil to argue that there is a substantial phase change in the
coil current along the coil.

Please understand exactly what I am saying, Owen.

1. There is a *substantial* phase change in the *traveling-wave*
current along the coil. Traveling-wave current is hard to
measure in a standing-wave antenna but its phase yields
complete and accurate phase/delay information.

2. There is virtually *no* phase change in the *standing-wave*
current along the coil. Standing-wave current is easy to
measure in a standing-wave antenna but its phase yields
close to *zero phase/delay information*.

3. In a standing-wave antenna, the total current is primarily
standing-wave current. In a loaded mobile antenna, the standing-
wave current is approximately 90% of the total current thus
tending to mask the traveling-wave current.

W8JI's and W7EL's "measurements" were made using standing-
wave current. They should have instead used traveling-wave
current. It's an easy mistake to make but one would think,
after five years, it is time to admit the mistake.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:


Please understand exactly what I am saying, Owen.

1. There is a *substantial* phase change in the *traveling-wave*
current along the coil. Traveling-wave current is hard to
measure in a standing-wave antenna but its phase yields
complete and accurate phase/delay information.

2. There is virtually *no* phase change in the *standing-wave*
current along the coil. Standing-wave current is easy to
measure in a standing-wave antenna but its phase yields
close to *zero phase/delay information*.

3. In a standing-wave antenna, the total current is primarily
standing-wave current. In a loaded mobile antenna, the standing-
wave current is approximately 90% of the total current thus
tending to mask the traveling-wave current.

Honestly, Cecil, it's pretty hard to know what you mean considering
the reckless way you throw around the term 'phase'. I'll grant that
you might know what you mean, but I don't see how you can expect
anyone else to.

73, ac6xg

Jim Kelley wrote:
Honestly, Cecil, it's pretty hard to know what you mean considering the
reckless way you throw around the term 'phase'. I'll grant that you
might know what you mean, but I don't see how you can expect anyone else
to.

Jim, if you have trouble understanding the word "phase",
look it up in a technical dictionary. I don't have time
to waste my time teaching everyone the principles of AC
waves in EE201.

But assuming some others are having the same problem as
you: From the IEEE Dictionary:

"phase - The fractional part t/P of the period P through
which t has advanced relative to an arbitrary origin."

FYI: For a signal proportional to cos(x)*cos(wt), the
phase doesn't change with 'x'. That's why standing wave
current cannot be used to measure delay.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

Jim Kelley wrote:

Honestly, Cecil, it's pretty hard to know what you mean considering
the reckless way you throw around the term 'phase'. I'll grant that
you might know what you mean, but I don't see how you can expect
anyone else to.


Jim, if you have trouble understanding the word "phase",
look it up in a technical dictionary. I don't have time
to waste my time teaching everyone the principles of AC
waves in EE201.

Thanks. Sorry for the unfinished thought. I meant that because of the
reckless way you use the term, I don't know how you expect others to
know what you intend by it when you use it.

FYI: For a signal proportional to cos(x)*cos(wt), the
phase doesn't change with 'x'. That's why standing wave
current cannot be used to measure delay.

Perfect example. The phase of a cosine wave at it's absolute maximum
amplitude is either 0 or 180 degrees. Each point along a sinusoidal
plot represents a different phase angle. Phase varies with time at a
fixed position, or varies with position at a fixed time. For it to
have meaning there must be a reference. You have a habit of switching
references without noticing or making note of it. This makes some of
your comments a bit confused sounding, if not blatantly inaccurate.

With regard to your comment above, if the maximum amplitude and period
of a sinusoidal wave are both known, then given any instantaneous
amplitude and, knowing whether the slope is positive or negative, the
instantaneous phase can be readily determined. FYI: Phase angle (wt)
is found on the x axis of a sinusoidal plot. When period or
wavelength and length are equated, as is the case with a resonant
antenna then phase and position are functionally related.

73, ac6xg

Jim Kelley wrote:
You have a habit of switching
references without noticing or making note of it. This makes some of
your comments a bit confused sounding, if not blatantly inaccurate.

Jim, it's all your fault for not being telepathic. :-)
I admit that my thought processes are somewhat chaotic
but remember, order often comes out of chaos. I've
experienced an epiphany or two in my time.

I also have a bad habit of declaring something invalid
when it is only irrelevant. It is the conclusions drawn
from irrelevant measurements that are invalid, not the
measurements themselves.

The convention that I try to use is the EZNEC convention.
Everything is referenced to the source signal. When I say
the phase of a standing wave is unchanging, I mean that it
has the same phase as the source signal at the feedpoint
and is the same phase as reported by EZNEC. I apologize for
not being clear about that.

With regard to your comment above, if the maximum amplitude and period
of a sinusoidal wave are both known, then given any instantaneous
amplitude and, knowing whether the slope is positive or negative, the
instantaneous phase can be readily determined.

Take I = K1*cos(x)*cos(wt), a standing-wave equation.
Let t be any fixed value. cos(x) is an amplitude value
and does NOT vary with time. Therefore, the phase of the
standing-wave signal is constant at any particular time
and does NOT depend upon position along the wire or coil.

Now take I = K2*cos(x+wt), a traveling-wave equation.
Let t be any fixed value. The length dimension 'x'
has an effect on phase, i.e. the phase of of the
signal indeed does depend upon BOTH position AND time.

Anyone who understands the math would not dare show
his ignorance by asserting that the delay through a
100T coil is 3 ns on 4 MHz or that the measured phase
shift through a loading coil is somehow proportional
to the delay through the coil in a standing-wave antenna.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

With regard to your comment above, if the maximum amplitude and period
of a sinusoidal wave are both known, then given any instantaneous
amplitude and, knowing whether the slope is positive or negative, the
instantaneous phase can be readily determined.


Take I = K1*cos(x)*cos(wt), a standing-wave equation.
Let t be any fixed value. cos(x) is an amplitude value
and does NOT vary with time. Therefore, the phase of the
standing-wave signal is constant at any particular time
and does NOT depend upon position along the wire or coil.

The item residing inside the parentheses of a sinusoidal function is
in fact the 'phase' of that function. In the expression above, at any
given time, amplitude is determined by the independent variable,
position. Accordingly, for any given position and time there is a
unique amplitude and phase.

Anyone who understands the math would not dare show
his ignorance by asserting that the delay through a
100T coil is 3 ns on 4 MHz or that the measured phase
shift through a loading coil is somehow proportional
to the delay through the coil in a standing-wave antenna.

In the face of such a redoubtable accusation I'm somewhat reluctant to
admit my view that a phase shift across a coil of this sort would in
fact be directly proportional to any propagation delay through that
coil.

73, ac6xg

Jim Kelley wrote:
In the face of such a redoubtable accusation I'm somewhat reluctant to
admit my view that a phase shift across a coil of this sort would in
fact be directly proportional to any propagation delay through that coil.

That's certainly true for traveling-wave current.
Definitely not true for standing-wave current which
doesn't change phase. I don't know that the comprehension
problem is here - maybe this graph will help.

http://www.w5dxp.com/travstnd.gif
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

Take I = K1*cos(x)*cos(wt), a standing-wave equation.
Let t be any fixed value. cos(x) is an amplitude value
and does NOT vary with time. Therefore, the phase of the
standing-wave signal is constant at any particular time
and does NOT depend upon position along the wire or coil.

Now take I = K2*cos(x+wt), a traveling-wave equation.
Let t be any fixed value. The length dimension 'x'
has an effect on phase, i.e. the phase of of the
signal indeed does depend upon BOTH position AND time.


Cecil,

I know what you are trying to say, but you got the message screwed up.
If 't' is fixed, then the equations are essentially the same with regard
to 'x'. That is typical; a snapshot in time does not say much about the
wave behavior.

73,
Gene
W4SZ

Gene Fuller wrote:
Cecil Moore wrote:

Take I = K1*cos(x)*cos(wt), a standing-wave equation.
Let t be any fixed value. cos(x) is an amplitude value
and does NOT vary with time. Therefore, the phase of the
standing-wave signal is constant at any particular time
and does NOT depend upon position along the wire or coil.

Now take I = K2*cos(x+wt), a traveling-wave equation.
Let t be any fixed value. The length dimension 'x'
has an effect on phase, i.e. the phase of of the
signal indeed does depend upon BOTH position AND time.


Cecil,

I know what you are trying to say, but you got the message screwed up.
If 't' is fixed, then the equations are essentially the same with regard
to 'x'. That is typical; a snapshot in time does not say much about the
wave behavior.

73,
Gene
W4SZ

It's generally cos(kx), but maybe Cecil is using a wave where k = 1,
that is, the wavelength is 2*Pi.
73,
Tom Donaly, KA6RUH

Jim Kelley wrote:


Cecil Moore wrote:

Jim Kelley wrote:

Honestly, Cecil, it's pretty hard to know what you mean considering
the reckless way you throw around the term 'phase'. I'll grant that
you might know what you mean, but I don't see how you can expect
anyone else to.


Jim, if you have trouble understanding the word "phase",
look it up in a technical dictionary. I don't have time
to waste my time teaching everyone the principles of AC
waves in EE201.

Thanks. Sorry for the unfinished thought. I meant that because of the
reckless way you use the term, I don't know how you expect others to
know what you intend by it when you use it.

FYI: For a signal proportional to cos(x)*cos(wt), the
phase doesn't change with 'x'. That's why standing wave
current cannot be used to measure delay.

Perfect example. The phase of a cosine wave at it's absolute maximum
amplitude is either 0 or 180 degrees. Each point along a sinusoidal
plot represents a different phase angle. Phase varies with time at a
fixed position, or varies with position at a fixed time. For it to have
meaning there must be a reference. You have a habit of switching
references without noticing or making note of it. This makes some of
your comments a bit confused sounding, if not blatantly inaccurate.

With regard to your comment above, if the maximum amplitude and period
of a sinusoidal wave are both known, then given any instantaneous
amplitude and, knowing whether the slope is positive or negative, the
instantaneous phase can be readily determined. FYI: Phase angle (wt) is
found on the x axis of a sinusoidal plot. When period or wavelength and
length are equated, as is the case with a resonant antenna then phase
and position are functionally related.

73, ac6xg

It's hardly surprising that Cecil thinks there's no phase information in
a standing wave, since he leaves it out on purpose. "Cos(x)*Cos(wt)" is
just flat wrong. It's supposed to be "Cos(x + d/2)*e^(i(wt + d/2))." "d"
is the phase difference between a wave traveling in the forward
direction and an equal amplitude wave traveling in the opposite
direction. This is pretty poor shooting for a guy who claims a
degree in symbol slinging.
73,
Tom Donaly, KA6RUH